Process for coloring the image on photographic plates, films, or the like



Patented- Nov. 27, 1928. z p M I i "NITED STATES GEOFFREY WHEELER, OF LONDON, ENGLAND.

PROCESS FOR COLORING THE IMAGE ON PHOTOGRAPHIC PLATES, FILMS, OR. THE LIKE.

No Drawing. Application filed January 19, 1927, Serial No. 162,204, and in Great Britain February 27, 1926.

through orange toa yellow in the parts where the silver deposit is lightest. 'The image representing the blue or blue to green color value can be appropriately dyed and then both'sides of the plate or either side so alone, can be chemically toned as above mentioned. When only one side is to be treated the side not undergoing treatment is suitably protected.

' In carrying the invention into practice, by

Way of example, the print or positive is immersed for about two minutes in a bleaching bath containing about 0.5% of chromic acid and about'0.5% of potassium ferricyanide, which may be quantities of a 1% solution of chromic acid. and of a 1% solution of potassiumferricyanide or other equivalent reagent. The film after removal from this bath, is rinsed in water, immersed for about three minutes in a 1% solution of sodium bisulphite and washed for about ten mniutes, preferably in running -water. The above baths and the rinsing water are preferably at a temperature between this bath, the unmordanted dye diffuses into 50 and 60 degrees F.

the solution and by continuing the treatment After the superfluous moisture has been the dye is decolorized in the parts of the drained of)? or otherwise removed, the film image where the silver deposit is lightest. is dyed. For the red side an aqueous solution 1 During this operation the image is converted of basic magenta (diaminomethyl-fuchsoni- 30 to a substantially transparent compound of monium chloride) induline scarlet (amino- $5 a yellow color. In the final result the densest ethyl-tolunaphthazonium chloride), or azine part of the image is colored by the dye to scarlet, (diamino-methyl-ditolazomum chloone tint, the amount of this coloration by the .ride), may be used. The dye is ground -to a dye becoming gradually less in the lighter fine powder and mixed gradually whilst heparts until in the lightest parts practically no lng stirred with a suificient quantity of W te dye is retained, such parts being colored a at 12 degreesF. Whenthe dye has disyellow tint only, as a result of the chemical V d, an addltional quantity of Water at toning.

. atmospheric temperature may be added to The improved process can be employed to m ke, for example in the case of basic ma.- produce colored transparencies in which opgcn a (d1ammomethyl-fuchsommonium chlo- .posite sides of films or plates coated on both a t0 Solutioll- T1118 Solutlon sides, are treated with dyes of different colors.

is filtered before use, and the addition of a The images on the opposite sides of the plate Small Percentage of acetlc acid y be "found are preferably produced from negatives givadvisable.

45 ing different color values of the object photothe b.1116 Sid6 methylene blue 23 graphed. The two sides of the film or plate (t t yl lp hi m m chlocan be treated separately or simultaneously, (Z1110 double of m t y .the opposite sides being treated with suitable ethyl dlammo-diphenazthlonium chloride) or dyes or mixtures of dyes. As a result of this turquoise blue (zinc double chloride .of tetratreatment the image representing, for exam- This invention relates to an improved proc-- ess for coloring the image on photographic plates, films or the like.

According to this invention the image on a 5 photographic film is toned by a solution of titanium trichloride converting the silver image to a compound of a yellow color. The said invention also contemplates a combination of chemical toning and dye toning, the

10 chemical toning being preferably effected as a part of the subsequent treatment of they dyed image. For this purpose, by Way of example, the print is first treated with a solution of potassium ferricyanide and 15 chromic acid or other equivalent reagent for a sulficient time to thoroughly bleach the silver image.v It is then rinsed in Water to remove the surplus bleaching solution, immersed in a solution of a weak reducing agent 20 such as sodium bisulphite, and again washed. A solution of a suitable dye or mixture of dyes is then applied, after which the print is treated in a weak toning solution of ti tanous chloride or titanium trichloride. In

a 5 methyl diamino diphenyl p.- nitrotolylcar- 6 prepared by mixing equal 70 i ple, the red or red to yellow color value of the objest photographed, when treated in this manner, has a coloration varying according to the density of the silver deposit from 65 red in the parts where the silver is densest binol anhydide) can be employed. A 1% 'to 4% aqueous solution of methylene blue 2B (tetramethyl diamino-diphenaz-thionium chloride), can be used ground with water in a mortar and diluted according to requirements. A proportion, for example, 5 cc. of a. 4% solution of borax can'be added to each 100 cc. of the dye solution. This borax solution can be prepared by dissolving the borax in hot water, and when the borax is dissolved the solution is cooled care being however taken to avoid crystallization. When the borax solution is added to the dye solution, the mixture is stirred for five minutes, and filtered before use.

The dyed film is subsequently treated in a bath made up by adding to 100 cc. of water, 0.65 cc. of solution of titanium trichloride and 1 cc. of hydrochloric acid (sp. gr. 1.16). The titanium trichloridebath canbe work ed for only a limited period. This period can however be prolonged by an addition of citric accid to the bath, and still further prolonged by the additionof powdered zinc. Thus 0.2 cc. of 10% solution of citric acid and 0.1 grammes of powdered zinc can be added per 100 cc. of the acidulated titanium trichloride solution with good results. The zinc may advantageously be in a state of fine subdivision, otherwise 1t may settle inthe bath and its action be thus delayed. The film remains in this bath for from three to ten minutes after which it is washed in water for about two minutes and then finally dried.

The proportions of the reagents hereinabove specified are given only by way of example, some departure from the exact proportions being permissible, and other dye substances than those above enumerated can be employed according to the colors or tints it is desired to impart to the film;

I claim:

A process for coloring the image on photographic'films, wherein the image is bleached, subjected to the action of a reducing agent, dyed with a dye and toned with a solution of titanium trichloride.

'eEoEEREY WHEELER. 

